Laundry detergents are available in several different product formats like powders, granulates, liquids, gels or unit dose items such as tablets or pouches.
Especially unit dose items comply with consumer's desire for simplified dosage. But, laundry tablets and pouches exhibit a few drawbacks. Especially tablets show due to their high densification only a delayed dissolution and, thus, a delayed release of their ingredients. In order to improve dissolution rates without being detrimental to tablet strength several technical solutions have been found such as the use of disintegration aids. Since integration aids usually do not show further cleaning or conditioning properties, complexity and manufacturing costs are raised.
The disadvantage of pouches comprising liquid detergent is that incompatible ingredients cannot be formulated in one detergent. Additionally, the wrapping material such as polyvinyl alcohol often does not dissolute completely during the washing process and residues can be found on the fabrics.
Another alternative unit dose item comprises laundry detergents that are coated on water-insoluble substrates. The laundry article is added together with the laundry to the washing machine. During the washing process the coating dissolves and thereby releases its ingredients to the wash liquor.
WO 07/120867 A2 provides a laundry article which functions as a single product for washing and conditioning fabrics when added to the washing machine and then carried along with the wet clothes into the clothes dryer. The laundry article comprises a water-insoluble substrate onto which a minimum of two compositions is applied in “zones”. The water-insoluble substrate for the laundry article of the present invention is coated with a detergent composition and a fabric conditioning composition. In order to manufacture such a laundry article preferably a heated molten mixture of the particular compositions is coated onto the water-insoluble substrate.
Proteins, fats and starch often form constituents of persistent stains. In order to improve removal of such stains enzymes are commonly used in laundry detergents.
Especially due to high temperatures (70° C. to 80° C.) during the manufacturing process of such laundry articles enzymes cannot be present in the molten mixture of a detergent composition since enzymes are sensitive to temperature.
This problem can be solved by coating an extra enzyme-containing composition on the substrate of a laundry article. The enzyme-containing composition comprises an enzyme embedded in a matrix and wherein the matrix is composed of a material having a lower melting point as the detergent composition solidified on the substrate. Possible matrix materials comprise fatty acids, fatty acid soaps, polyols and mixtures thereof.
One problem associated with such a molten enzyme-containing composition, especially when the matrix material is a fatty acid soap, is its low viscosity. Due to the low viscosity of the molten enzyme-containing composition, the composition is difficult to apply to the substrate because the molten composition penetrates through the substrate and is discharged on the other side of the substrate. Additionally, such a coating is not aesthetically appealing to the user of the laundry article.
Usually, the viscosity can be adjusted with the help of a thickener. Since the molten enzyme-containing compositions have a low free water activity conventional thickeners such as poly(meth)acrylic acid based thickeners do not provide a sufficient high thickening effect.
Accordingly, it is an object of the present invention to provide a laundry article comprising a water-insoluble substrate coated with a detergent composition and an enzyme-containing composition, wherein the enzyme-containing composition can be applied to the substrate without any difficulties.
This object is achieved by a laundry article used for cleaning fabrics comprising:                a. a water-insoluble nonwoven substrate;        b. a detergent composition solidified on the substrate in at least one zone; and,        c. an enzyme-containing composition solidified on the substrate in at least one zone,wherein the enzyme-containing composition comprises an enzyme embedded in a matrix andwherein the matrix comprises a fatty acid soap and a shear activated thickener.        
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.